title: Characterization of carboxylesterase in skin mucus of Cirrhinus mrigala and its assessment as biomarker of organophosphate exposure.
abstract: Presence of carboxylesterase (CbE) activity in the skin mucus of Cirrhinus mrigala was investigated. CbE activity in skin mucus showed higher substrate preference for α-naphthyl acetate over p-nitrophenyl acetate. Four CbE isozymes-CbE-1, CbE-2, CbE-3, and CbE-4 were observed in skin mucus during zymography. The isozyme CbE-4 was characterized as typical serine esterase, whereas CbE-1, CbE-2, and CbE-3 were identified as sulphhydryl group-dependent serine esterases. In vitro treatment of skin mucus with the organophosphorus insecticide, Nuvan(®) showed strong inhibition of CbE activity. In vivo exposure of the fish to sublethal test concentrations (5 and 15 mg/l) of the insecticide also revealed significant inhibition of CbE activity in mucus. After the cessation of exposure, CbE activity recovered to its control level during the recovery periods. Thus, CbE activity in skin mucus could be considered a biomarker of the organophosphorus insecticide exposure to fish and a useful tool in monitoring environmental toxicity.
authors.affiliation: Skin Physiology Laboratory, Centre of Advanced Study, Department of Zoology, Banaras Hindu University, Varanasi, 221 005, India.
authors.forename: Ashwini Kumar
authors.initials: AK
authors.lastname: Nigam
authors.forename: Usha
authors.initials: U
authors.lastname: Kumari
authors.forename: Swati
authors.initials: S
authors.lastname: Mittal
authors.forename: Ajay Kumar
authors.initials: AK
authors.lastname: Mittal
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003530:Cyprinidae / Q000378:metabolism*; D004784:Environmental Monitoring / Q000379:methods; D029941:Fish Proteins / Q000378:metabolism*; D005506:Food Contamination / Q000032:analysis; D009093:Mucus / Q000201:enzymology*; D010755:Organophosphates / Q000378:metabolism*; D012867:Skin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D029941:Fish Proteins; D010755:Organophosphates; D002265:Carboxylic Ester Hydrolases